When I was 15, “working” meant manning a cash register at a store in my local mall for minimum wage.

For 15-year-old Noa Mintz, it means heading down to a rented Midtown, Manhattan office building to oversee her company, Nannies by Noa.

In 2012, at just 12 years old, Mintz was inspired to launch her own nanny agency after noticing how much trouble her mother had finding a babysitter.

Nannies by Noa now boasts over 190 clients and rakes in almost half a million dollars annually. Not bad.

Mintz started the business with one goal in mind: To find a babysitter she approved of. Soon, she began helping her mother's friends find babysitters and nannies for their families.

Word spread and the business grew fast; in the past year alone, the clientele has tripled.

“I really had no expectations, but I figured I'd try,” Mintz told CNN Money of her decision to launch the company.

When she began, Mintz charged between just $100 and $200 for her services, hoping to “get trust before people wanted to commit to money.” (“I wasn't charging enough,” she admits today.)

Still, that trust was well-earned. Each potential client is subjected to a rigorous application process, which includes filling out a résumé, completing an in-person interview with a trained nanny, providing references, undergoing background checks and completing a phone interview.

At first, Mintz handled all of the work herself, but as her clientele grew, she found herself overwhelmed trying to balance the 40-hour-per-week workload with her 8th grade course load.

She hired 26-year-old Allison Johnson to oversee all aspects of the business while Mintz was otherwise engaged with school.

Today, Mintz collects a standard 15 percent of her nannies' gross salaries, which typically range between $50,000 and $80,000.

With 25 full-time nannies and 50 babysitters working an average of 15 hours per week, unconfirmed estimates put Mintz' yearly income around $375,000.

For now, with her company being run by de facto CEO Johnson, Mintz hopes to focus her energy on herself.

“I don't know where I'll be in a few years,” she admits. “I want to enjoy my young adult years.”

And as for future business endeavors?

“First I need to finish high school,” she says, “and then perhaps I'll launch another company. We'll see.”